Local anesthetics are pharmaceutical materials useful in the relief of many discomforts such as teething, sunburn, pruritus, various dental and surgical procedures, for temporary relief of minor burns, cuts, scratches, nonpoisonous insect bites, poison ivy and other minor skin irritations. They may also be used for postpartum care. In brief, local anesthetics may be employed for diminishing the pain in a restricted area as distinguished from general anesthetics used for eliminating the perception of all stimuli. Many of the known local anesthetics are derivatives of p-aminobenzoic acid; for example, procaine, tetracaine and butacaine. Lidocaine is another type of local anesthetic in wide use.
There is constant interest in developing compounds showing improvement in the therapeutic index over conventional anesthetics such as the above and others. In particular, there is a striving to discover local anesthetics which have a relatively short onset and longer duration of action than those presently employed.